Renal tumor with intact envelope and clear boundary suggests that it may be a benign tumor of the kidney, or the malignant tumor has not yet invaded out of the kidney, i.e., early renal cancer. There are benign tumors and malignant tumors of the kidney. The most common benign tumors are renal cysts, renal vascular smooth muscle lipoma, etc. Benign tumors usually have a complete envelope, and there is no risk of metastasis, and after surgical resection, the envelope is usually more complete with clear boundaries. The most common malignant tumor of kidney is clear cell carcinoma, if the diameter of renal cancer is relatively small, less than 4 cm, and has not yet broken through the renal peritoneum, the completion of resection of the tumor can also show that the peritoneum is relatively intact, with clear boundaries, suggesting that infiltration has not yet occurred. Therefore, we cannot judge the benign or malignant by the periphery and boundary of the kidney, but have to do pathological examination to confirm the diagnosis, and choose the surgical method and subsequent treatment according to the pathological results.